Synonymy of Idiococcobius Hayat with Coccobius Ratzeburg (Hymenoptera, Aphelinidae): evidenced by a new species from Malaysian Borneo

Idiococcobius Hayat, syn. nov., is synonymised with Coccobius Ratzeburg, based on morphological and molecular data from a new species of Coccobius from Malaysian Borneo. The new species is sufficiently similar morphologically to the type species of Idiococcobius to place it unambiguously within that genus, but molecular data from the new species, and a reassessment of the morphology of Idiococcobius, indicate synonymy of the two genera. Idiococcobius encarsoides Hayat is therefore transferred to Coccobius; resulting in the new combination: Coccobius encarsoides (Hayat), comb. nov. Coccobius islandicus Geng & Polaszek, sp. nov, is described from morphology and DNA sequence data.


Introduction
The genus Idiococcobius Hayat,2010 was described for an unusual species of aphelinid considered to be "extremely close to Coccobius…" (Hayat and Khan 2010), but to have affinity with some Encarsia species, hence the species name I. encarsoides Hayat, 2010. The morphological characters that purport to establish Idiococcobius as a valid genus also occur in a recently discovered new species from Malaysian Borneo. Molecular analysis of the latter species places it firmly within Coccobius. The affinities (and differences) between Coccobius encarsoides (Hayat) and Coccobius islandicus Geng & Polaszek, sp. nov., are detailed and discussed below.

Morphological study
The single specimen of the new Coccobius species was collected in Sabah, Malaysian Borneo using a yellow pan trap. After "non-destructive" DNA extraction (see below), the specimen was dissected and mounted dorsally in Canada balsam on a slide following the method of Noyes (1982) with modifications for dealing with ProteinaseK processed specimens (AP, unpublished). Morphological terminology follows Hayat and Khan (2010).
Photographs were taken with a digital CCD camera attached to an Olympus BX63 compound microscope equipped with differential interference contrast. All measurements were taken from slide-mounted specimens. The holotype is deposited in the Natural History Museum, London, UK The following abbreviation is used:

DNA sequencing
Genomic DNA extraction was undertaken using the protocol in Polaszek et al. (2013), which leaves the sclerotized parts of the specimen intact. The specimen was then mounted in Canada balsam on a microscope slide (see above). Primer sequences are given in Table 1. A total of 25μl per reaction with 2.5μl 10× NH4 Reaction Buffer, 1.5μl 50mM MgCl2 Solution, 0.5μl dNTP's, 1μl of each primer, 0.5μl BIOTAQ DNA Polymerase, and 6μl DNA template. PCR amplifications included a pre-cycle denaturation step for 5 min at 94 °C and a final post-cycle extension step at 72 °C for 5 min (Table 1). DNA was sequenced at the Natural History Museum Life Sciences DNA Sequencing Facility (London) using the same primers used for the PCR. Forward and reverse sequences were assembled and corrected using Sequencher version 4.8. The 28S sequence of Coccobius islandicus Geng & Polaszek, sp.nov., has been deposited in Gen-Bank under accession no MT350291. The resulting COI sequence was short, and not useful for comparative analysis. However, a 28S D2 sequence of 744bp was obtained and sent (including the trace file) to the 3 rd author (JM) for comparison and analysis with his substantial database of 147 Coccobius DNA sequences.

Morphology
C. islandicus Geng & Polaszek, sp. nov., shares a number of apparent synapomorphies with C. encarsoides (Hayat) as follows: pronotum medially membranous; mid lobe of mesoscutum with a reduced number of setae arranged bilaterally; fore wing narrow with very long marginal fringe (more than 2/3 the maximum wing width); submarginal vein with a single seta. These characters, not previously encountered in described Coccobius species, clearly indicate that the two species are closely related.
The morphological differences between the two species, tabulated below, strongly support recognition of C. islandicus as a new species.   (Fig. 1B). Pronotum medially membranous; mid lobe of mesoscutum with 8 setae (Fig. 2A); maximum length of marginal fringe of fore wing 0.68× wing width.
Mid lobe of mesoscutum with 8 setae arranged in approximate bilateral symmetry. Sculpture of mesoscutal mid lobe consisting of large irregular reticulations, that of scutellum with longitudinal elements. Scutellum with 2+2 setae, the front pair placed slightly behind the level of the scutellar sensilla ( Fig. 2A). Wings elongate. Fore wing 3.22× as long as wide, marginal fringe 0.68× as long as maximum wing width, submarginal vein with 1 seta, stigmal vein sensilla in a cluster of 4 (Fig. 1C). Hind wing 7× as long as wide, marginal fringe 1.6× as long as maximum wing width. Mid tibial spur 1.29× mid basitarsus.
Male. Unknown. Host. Unknown. Distribution. Sabah, Malaysian Borneo. Etymology. "island"-(icus) is the latinised form of the English word "Iceland", in this case referring to a British food retailer that has banned the use of palm oil in its products. The species name does not imply any endorsement by the authors of this retailer's products.

Discussion
Hayat (in Hayat and Khan 2010) described Idiococcobius as a genus he considered to be close to, but distinct from, Coccobius, based on a combination of characters that had not previously been encountered in any Coccobius species known to him at that time. The medially membranous pronotum, reduced and bilaterally symmetrical mesoscutal setae, and narrow fore wing with long marginal fringe, all suggested possible affinity with Encarsia, a genus not particularly close to Coccobius. These characters clearly merited the description of a new genus, with the Encarsia similarities conveyed in the species name "encarsoides". These kinds of reduction characters appear to be common not only across the Aphelinidae, but among many chalcids and beyond. Setal reduction and wing narrowing (as seen here), reduction in tarsal segment number and antennomeres are all processes known to have occurred independently in multiple lineages, and have confounded traditional morphology-based taxonomy for so long. The development of relatively comprehensive molecular databases, even those (as herein) relying on a single gene, are extremely valuable for the unequivocal elucidation of an organism's true relationships. While not always perfect, when sample size is adequate and gene variability sufficient, their predictive power is considerable. Studies such as that described above are able both to contribute towards more stable classification as well as reveal widespread morphological convergence, especially in organisms with similar biology.